The present invention relates to signal supply apparatus, methods for examining signal supply apparatus, and semiconductor devices, electro-optical apparatus and other electronic apparatus using the same.
FIG. 9 depicts a conventional signal supply apparatus 100 tat includes a voltage follower group 102 that performs impedance conversion of multiple input voltages VIN. The voltage follower group 102 includes N number of voltage followers 102-1xcx9c102-N. Outputs O1xcx9cON are provided an output lines of the N number of voltage followers 102-1xcx9c102-N, respectively.
In the conventional apparatus described above for performing impedance conversion of the input voltages VIN by the respective plurality of impedance conversion circuits, when the performance of the apparatus is examined, the outputs O1xcx9cON of the respective voltage followers 102-1xcx9c102-N are independently measured and examined. However, it takes a substantially long time to examine output characteristics of each of the respective voltage followers 102-1xcx9c102-N in succession.
Aspects of the present invention can provide a signal supply apparatus and a method for examining the signal supply apparatus in which good or bad performances of a plurality of impedance conversion circuits can be examined in one lot, and a semiconductor device, an electro-optical apparatus, and an electronic apparatus that use the improved signal supply apparatus. In accordance with one embodiment of the present invention, in a method for examining a signal supply apparatus in which signals having specified voltages supplied from a plurality of signal supply sources are subject to impedance conversion, respectively, by a plurality of impedance conversion devices, and supplied to a plurality of output lines, respectively, wherein each of the plurality of output lines is short-circuited upon examination, and a current value detected on the short-circuited tines is compared with a specified current value to thereby determine as to whether the signal supply apparatus is good or bad.
Also, a signal supply apparatus in accordance with aspects of the present invention comprises a plurality of switching elements provided for the corresponding respective plurality of output lines, a rest terminal for inputting a test signal that controls open and close of each of the plurality of switching elements, and a detection terminal that is connected to the short-circuited lines.
In this manner, the respective impedance conversion devices cause deviations in their performances due to offset voltages. Therefore, when input signals are subject to impedance conversion by the respective impedance conversion devices and outputted, deviations are generated in the output signals. In the present invention, deviations are not independently measured based on the output signals of the respective impedance conversion devices. Instead, a composite current value obtained by short-circuiting output lines of the respective impedance conversion devices is measured. Then the measured composite current value is compared with a specified current value to thereby determine whether the apparatus itself is good or bad. As a result, the time for examining the performance of the signal supply apparatus can be shortened.
Also, in accordance with another embodiment of the present invention, in a method for examining a signal supply apparatus in which signals are subject to impedance conversion by a plurality of impedance conversion devices, respectively, and supplied to a plurality of output lines, the method is characterized in that each of the plurality of output lines is short-circuited upon examination, and a composite current consumption value of the plurality of impedance conversion devices is compared with a specified current value to thereby determine as to whether the signal supply apparatus is good or bad.
Also, a signal supply apparatus in accordance with aspects of the present invention comprises a plurality of switching elements provided for the corresponding respective plurality of output lines, a test terminal for inputting a test signal that controls open and close of each of the plurality of switching elements, a short-circuit line that short-circuits the plurality of output lines when the plurality of switching elements are operated, and a detection terminal for detecting the composite current consumption value.
Respective impedance conversion devices cause deviations in their voltages of input signals due to offset voltages. Therefore, the respective impedance conversion devices themselves consume power supply current. According to aspects of the present invention, the current consumption of each of the impedance conversion devices is compared with a specified current consumption value to thereby determine whether the apparatus itself is good or bad. As a result, the time for examining the performance of the signal supply apparatus can be shortened.
In addition, the signal supply apparatus can be used as a driver device to drive each of the plurality of data lines in a display section using electro-optical elements. As a result a determination can be made as to whether the data line driver IC itself is good or bad.
Also, the data line driver IC can be characterized in that, after a voltage is supplied to the test terminal and each of the plurality of switching elements is operated, a voltage with a voltage width range corresponding to xc2x1(LSB)/2 with respect to the signal having the specified voltage to be supplied to the electro-optical element is supplied trough the detection terminal to the short-circuit line, a minimum value among the current values detected at the detection terminal in response thereto is compared with a specified current value to make a good-or-bad determination.
In this manner, a voltage V with a voltage width range corresponding to xc2x1(LSB)/2 with respect to the specified voltage is supplied to each of the short-circuited line of the output line of the data line driver IC of the electro-optical apparatus.
In the relation between the voltage V and the composite current value I, a current value Imin that minimizes the composite current value I is compared with a predetermined current value, such that whether the apparatus is good or bad can be determined.
Also, in the data line driver IC, the specified voltage is characterized in that the specified voltage is set as a voltage that is supplied to the electro-optical element when the display section displays an intermediate gradation.
A curve representing light transmissivity of a display section of an electro-optical apparatus with respect to input voltages is not generally composed of linear lines, and relatively speaking, an input voltage with a higher accuracy needs to be applied for intermediate gradations.
Also, the data line driver IC can be applied to an electro-optical apparatus, and the electro-optical apparatus can be applied to an electronic apparatus.